Slack adjusters, and in particular, automatic slack adjusters, are required to be accurately positioned when installed in order to permit properly controlled operation of a vehicle's brakes with which the adjusters are operably associated.
A typical automatic slack adjuster has an elongated body having one end fitted with means for removably coupling the adjuster for rotation with a brake control shaft and an opposite end having an opening for removably receiving a bearing pin carried by a clevis adjustably mounted on a brake actuating push rod, and an adjustment link having one end slidably supported by the body and an opposite end formed with a bore opening for removably receiving a connecting pin carried by the clevis. In mounting of the slack adjuster, care must be exercised to ensure that a line drawn axially of the push rod and through centers of openings of the clevis, which receive the bearing and connecting pins, is disposed at a predetermined angle relative to a line drawn through the centers of the opening formed in the opposite end of the adjuster body and the brake control shaft, as determined by system operating requirements.
Heretofore, it has been proposed to employ plate-like gages as an aid to the accurate installation of slack adjusters. However, presently available gages are difficult to use in that they rely on a user's steady hand and sight to achieve proper positioning of the centers of the clevis openings relative to the center of the brake control shaft, and their use ofttimes results in faulty installations.